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    <meta charset="UTF-8">
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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
        /* 
           需求分析：
           1.提示用户输入一个数
           2.判断如果小于10，则补零
        */

        let num= prompt('请输入一个数');
        //if (num<10){
        //    num='0'+num;
        //}else{
        //    num;
        // }
        num=num<10? '0' +num :num;
        console.log(num);
    </script>
</body>
</html>